1. The Field of the Invention
The present invention relates to polymeric optical substrates and coatings thereon. More specifically, the invention relates to a method for pretreating polymeric optical substrates in order to improve the adhesion of optical coatings to the substrates.
2. The Relevant Technology
Polymeric optical substrates such as polycarbonate and polymethyl methacrylate ("PMMA") are useful in a variety of different optical components such as lenses, optical filters, and the like. Commonly, such polymeric optical substrates are coated with optical coatings, such as interference coatings, antireflective coatings, and other conventional optical coatings.
However, adhesion of optical coatings onto these and other polymeric optical substrates is often problematic and unsatisfactory. Lack of sufficient adhesion of coatings to polymeric optical substrates can result in premature peeling or delamination of the coatings from the substrates, easy scratching of the coatings, and uneven distribution of coating layers on substrates.
It is believed that lack of sufficient adhesion of coatings to polymeric optical substrates is due in part to the ease in damaging the polymeric material during exposure to energetic particles before a coating is applied. This damage includes loss of material through etching and ablation, bond scission, and forming of weak boundary layers in the polymeric material.